particle doubts: blender 2.8
In order to edit individual buildings you will have to edit the actual models in the "buildings" collection, "Building1", "Building2", etc. The buildings appearing on the emitter plane are merely linked duplicates from the actual models, and not editable on the go.



To hide the base plane object, you have to go in the particle settings and uncheck "show emitter" from rendering or/and from the viewport, depending on what you want :